1. Field of the Invention
The present invention relates to an airbag used for an airbag apparatus for a front passenger's seat mounted on a top plane of the instrument panel in front of the front passenger's seat.
2. Description of Related Art
In a conventional airbag for a front passenger's seat shown in JP 2006-103654, an airbag includes a passenger protection area on its rear side at full inflation. The passenger protection area includes a pair of shoulder restraining portions disposed laterally side by side at areas from a top side to the rear side of the fully inflated airbag. Each of the restraining portions projects continuously from the top side to the rear side of the airbag.
The above conventional airbag for a front passenger's seat is formed by joining peripheral edges of an outer panel and an inner panel. The inner panel is composed of a pair of left and right cloth members having generally the same contours. The cloth members have such a structure as to laterally divide an area of the inner panel at full airbag inflation into two. The cloth members each has a band shape curved in a generally C shape, and are formed into the inner panel by being joined at respective inner circumferential edges. The joint portion, which is formed when joining the inner circumferential edges, provides a circumferential edge of a communication area communicating the left and right shoulder restraining portions.
The joint portion formed when joining the inner circumferential edges of the cloth members for the inner panel includes a corner portion where a curvature is partially large. The corner portion is likely to be so deformed as to lessen its curvature when subjected to stress concentration upon airbag deployment, which results in less projection of the shoulder restraining portions. In light of this, there is a room for improvement in stabilizing the inflated contour of the airbag for proper protection of a passenger.